WEDNESDAY, Jan. 6 (HealthDay News) -- Fat mass plays an important role in building bone mass in teenage girls and having too little may increase their risk of osteoporosis later in life, new research has found.

In the study, researchers measured cortical bone mass (the hard outer layer of bone) in 4,005 girls and boys, mean age 15.5 years. The results showed that fat mass had a positive influence on bone mass, particularly in girls, where the effect was about 70% greater than in boys.

The study is scheduled for publication in the February issue of the Journal of Clinical Endocrinology & Metabolism.

"The effect of fat mass on bone mass appears to be strongest in girls," study lead author Jonathan Tobias, of the University of Bristol in England, said in an Endocrine Society news release. "Girls clearly have more fat mass than boys and our findings show that whereas the greater lean mass in boys contributes to their greater cortical bone mass, this effect is partly counteracted by the greater fat mass in girls," Tobias explained.

"Fat mass in girls during puberty may have a long-term impact on bone health as they grow into adulthood. Excessive reduction in fat mass could have adverse effects on the developing skeleton particularly in girls, leading to an increased risk of osteoporosis later in life," Tobias said.